Hook and loop fasteners such as Velcro® are well known ways for mechanically fastening together two separate objects or things without the use of an adhesive like glue. These fasteners including a hook portion coupled to one of the two objects and a loop portion coupled to the other of the two objects. To fasten the objects together, simply press the hook portion into the loop portion. An interesting characteristic of hook and loop fasteners is that the mechanical bonds created are relatively strong if one attempts to pull apart the hook portion in a direction perpendicular to the loop portion, while the mechanical bonds are less strong if one simply peels the hook portion away from the loop portion in a direction not perpendicular to the loop portion.
By contrast, conventional chemical bonding allows objects or things to be coupled together by applying an adhesive between the two surfaces that cures to couple together the two objects. The objects are bonded together by curing the adhesive. This creates essentially an irreversible bond between the objects (i.e. the bond cannot subsequently be debonded and bonded for multiple cycles).